The bad news? That extension is only for the paperwork itself, and not any tax payments due to the Internal Revenue Service.

“What many people do not realize is that filing for an extension only extends the time for the filing of the proper IRS forms,” said Bob Phillips, a certified public accountant and managing principal at Spectrum Management Group in Indianapolis. “It doesn’t extend the time to pay taxes that are owed. If you owe tax, you still must pay it by April 15 in order to avoid penalties and interest.”

Specifically, the IRS charges a combined penalty of 5% for each month that your return is late — 4.5% for late filing, and 0.5% for late payment.

Asking for an extension will indeed save you the pain of that larger penalty levied on those who don’t file at all, but you still must pay your taxes by April 15 or face an additional 0.5% penalty on that bill. In fact, when you ask for an extension via form 4868, Part II of that form requires you to fill out your estimated tax liability to ensure you acknowledge whether you owe something.

If you owe the IRS money and have all the proper tax forms, then, it’s probably best to simply bite the bullet and file your taxes immediately.

After all, your bill isn’t going to go away, and delaying payment may simply result in interest charges or other penalties.

If you can’t pay your tax bill, an extension may not defray the costs but can, indeed, help you negotiate payment terms with the Internal Revenue Service. For those who owe $50,000 or less in individual taxes (and penalties), the IRS offers payment plan options to spread your tax bill out over several months — but only for those who have filed all tax forms.

Thus, asking for an extension is much more preferable than not filing anything, which could render you ineligible for a payment plan as well as result in penalties.

Not everyone looking for more time is trying to duck paying the tax man, of course. Some folks simply haven’t received the appropriate paperwork yet and can’t meet the deadline through no fault of their own.

Phillips said that, in his experience, the need for an extension “usually is due to not having all the information they need to properly complete their tax return by April 15.” Frequently, this is a problem faced by investment in a partnership or business, where paperwork is a bit more complex and isn’t always sent out promptly.

In these cases, an extension is a no-brainer. Filing incomplete taxes not only may cause you to miss important deductions, but also can leave you open to an IRS audit if you don’t produce documents they are expecting to receive at tax time.

Just remember to make that estimated payment in good faith, Phillips notes.

And if you don’t owe any taxes? Well, it may be tempting to think that the April 15 deadline doesn’t apply to you. But even in these cases, it’s important to make a formal request for an extension even if you don’t have any prepayment to make.

That’s because even if your itemized return shows no tax burden or a tax refund due, the IRS doesn’t have any of that specific information; you may actually have an outstanding bill by their calculations. Filing your taxes, then, is a way to make sure you’re on the same page as the tax man and that no undeserved penalties are levied.